This invention relates to a novel monoclonal antibody effective for the diagnosis of human cancers, a hybridoma producing the antibody; a method for manufacturing the antibody and a diagnostic aid using the antibody.
The present invention provides a monoclonal antibody which reacts specifically with fucosylceramide of a ceramide-mono-glycoside fraction contained in neutral glycolipid extracted from human cancer tissues, a hybridoma which produces the antibody, a method for manufacturing the antibody by using the hybridoma and a diagnostic aid using the antibody.
Since a monoclonal antibody preparation technique was established in 1975 by Kohler and Milstein [Nature 256:495 (1975)], numerous investigators have tried to prepare a monoclonal antibody which specifically recognizes cancer tissues up to now. They employed a method of selecting a hybridoma, which is unreactive with human normal cells but recognizes human cancer cells by directly immunizing a mouse with the human cancer cells. It turned out that many of the tumor antigens which were recognized by the monoclonal antibody obtained by the above-described method were sugar chain antigens [S. Hakomori, Scientific American 254, 32.41 (1986)].
As typical examples thereof, CA-19-9, sialyl SSEA-1, etc. can be mentioned. They have been already used widely in the clinical field as a marker of cancer [Reiji Kannagi, Clinical Pathology XXXTV: 11, 1247.about.1264 (1986)]. However, these antigens have sugar chains carrying 5 or more sugars. With respect to a short-sugar chain antigen, it is considered that the research thereon is still insufficient although their ability of being important tumor-antigens has been discussed already.
Fucosylceramide (structural formula: L-Fuc.alpha.l-1Cer) composed of one fucose being linked to ceramide (lipid-part) was isolated from colon cancer tissues by Senitiroh Hakomori et al in 1976 and there was a chance that the fucosylceramide was glycolipid which was expressed specifically in human cancers [JBC, 251, 2385.about.2387 (1976)]. In addition, they immunized a rabbit with chemically synthesized fucosylceramide to prepare a polyclonal antibody. However, this polyclonal antibody was not specific to fucosylceramide alone but cross-reactive to ceramide and galactosylceramide, so that it was impossible to accurately determine the presence of fucosylceramide in human cancer cells or tissues [Biochemistry, 21, 928.about.934 (1982)].